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<script src="https://snack.expo.io/embed.js" defer="defer"></script><title data-react-helmet="true">State · React Native</title><meta data-react-helmet="true" property="twitter:image" content="https://reactnative.dev/img/logo-og.png"><meta data-react-helmet="true" name="twitter:image:alt" content="Image for React Native"><meta data-react-helmet="true" name="docsearch:language" content="en"><meta data-react-helmet="true" name="docsearch:version" content="current"><meta data-react-helmet="true" name="docsearch:docusaurus_tag" content="docs-default-current"><meta data-react-helmet="true" property="og:image" content="https://reactnative.dev/img/logo-og.png"><meta data-react-helmet="true" name="twitter:card" content="summary"><meta data-react-helmet="true" name="twitter:image" content="https://reactnative.dev/img/logo-og.png"><meta data-react-helmet="true" property="og:title" content="State · React Native"><meta data-react-helmet="true" name="description" content="There are two types of data that control a component: props and state. props are set by the parent and they are fixed throughout the lifetime of a component. For data that is going to change, we have to use state."><meta data-react-helmet="true" property="og:description" content="There are two types of data that control a component: props and state. props are set by the parent and they are fixed throughout the lifetime of a component. For data that is going to change, we have to use state."><meta data-react-helmet="true" property="og:url" content="https://reactnative.dev/docs/next/state"><link data-react-helmet="true" rel="shortcut icon" href="/img/favicon.ico"><link data-react-helmet="true" rel="preconnect" href="https://BH4D9OD16A-dsn.algolia.net" crossorigin="anonymous"><link data-react-helmet="true" rel="canonical" href="https://reactnative.dev/docs/next/state"><link rel="stylesheet" href="/styles.fccefeba.css">
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<script>!function(){function t(t){document.documentElement.setAttribute("data-theme",t)}var e=function(){var t=null;try{t=localStorage.getItem("theme")}catch(t){}return t}();t(null!==e?e:"light")}()</script><div id="__docusaurus">
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<nav class="navbar navbar--fixed-top navbar--dark"><div class="navbar__inner"><div class="navbar__items"><div aria-label="Navigation bar toggle" class="navbar__toggle" role="button" tabindex="0"><svg xmlns="http://www.w3.org/2000/svg" width="30" height="30" viewBox="0 0 30 30" role="img" focusable="false"><title>Menu</title><path stroke="currentColor" stroke-linecap="round" stroke-miterlimit="10" stroke-width="2" d="M4 7h22M4 15h22M4 23h22"></path></svg></div><a class="navbar__brand" href="/"><img class="navbar__logo" src="/img/header_logo.svg" alt="React Native"><strong class="navbar__title">React Native</strong></a><div class="navbar__item dropdown dropdown--hoverable dropdown--left"><a class="navbar__item navbar__link" href="/docs/next/getting-started">Next</a><ul class="dropdown__menu"><li><a aria-current="page" class="dropdown__link dropdown__link--active" href="/docs/next/state">Next</a></li><li><a class="dropdown__link" href="/docs/state">0.63</a></li><li><a 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class="navbar-sidebar__backdrop"></div><div class="navbar-sidebar"><div class="navbar-sidebar__brand"><a class="navbar__brand" href="/"><img class="navbar__logo" src="/img/header_logo.svg" alt="React Native"><strong class="navbar__title">React Native</strong></a></div><div class="navbar-sidebar__items"><div class="menu"><ul class="menu__list"><li class="menu__list-item"><a class="menu__link" href="/docs/next/getting-started">Docs</a></li><li class="menu__list-item"><a class="menu__link" href="/docs/next/components-and-apis">Components</a></li><li class="menu__list-item"><a class="menu__link" href="/docs/next/accessibilityinfo">API</a></li><li class="menu__list-item"><a class="menu__link" href="/help">Community</a></li><li class="menu__list-item"><a class="menu__link" href="/blog">Blog</a></li><li class="menu__list-item"><a role="button" class="menu__link menu__link--sublist">Versions</a><ul class="menu__list"><li class="menu__list-item"><a aria-current="page" class="menu__link menu__link--active" href="/docs/next/state">Next</a></li><li class="menu__list-item"><a class="menu__link" href="/docs/state">0.63</a></li><li class="menu__list-item"><a class="menu__link" href="/docs/0.62/state">0.62</a></li><li class="menu__list-item"><a class="menu__link" href="/docs/0.61/state">0.61</a></li><li class="menu__list-item"><a class="menu__link" href="/docs/0.60/state">0.60</a></li><li class="menu__list-item"><a class="menu__link" href="/versions">All versions</a></li></ul></li><li class="menu__list-item"><a href="https://github.com/facebook/react-native" target="_blank" rel="noopener noreferrer" class="menu__link navbar-github-link" aria-label="GitHub repository"></a></li></ul></div></div></div></nav><div class="main-wrapper"><div class="docPage_2UBv"><main class="docMainContainer_1rYT"><div class="container padding-vert--lg docItemWrapper_1Hme"><div class="row"><div class="col docItemCol_2AGf"><div class="alert alert--warning margin-bottom--md" role="alert"><div>This is unreleased documentation for React Native <strong>Next</strong> version.</div><div class="margin-top--md">For up-to-date documentation, see the <strong><a href="/docs/state">latest version</a></strong> (0.63).</div></div><div class="docItemContainer_1tAC"><article><div><span class="badge badge--secondary">Version: Next</span></div><header><h1 class="docTitle_cWlf">State</h1></header><div class="markdown"><p>There are two types of data that control a component: <code>props</code> and <code>state</code>. <code>props</code> are set by the parent and they are fixed throughout the lifetime of a component. For data that is going to change, we have to use <code>state</code>.</p><p>In general, you should initialize <code>state</code> in the constructor, and then call <code>setState</code> when you want to change it.</p><p>For example, let's say we want to make text that blinks all the time. The text itself gets set once when the blinking component gets created, so the text itself is a <code>prop</code>. The "whether the text is currently on or off" changes over time, so that should be kept in <code>state</code>.</p><div class="snack-player" data-snack-name="State" data-snack-description="Example usage" data-snack-code="import%20React%2C%20%7B%20useState%2C%20useEffect%20%7D%20from%20'react'%3B%0Aimport%20%7B%20Text%2C%20View%20%7D%20from%20'react-native'%3B%0A%0Aconst%20Blink%20%3D%20(props)%20%3D%3E%20%7B%0A%20%20const%20%5BisShowingText%2C%20setIsShowingText%5D%20%3D%20useState(true)%3B%0A%0A%20%20%20useEffect(()%20%3D%3E%20%7B%0A%20%20%20%20%20const%20toggle%20%3D%20setInterval(()%20%3D%3E%20%7B%0A%20%20%20%20%20%20%20setIsShowingText(!isShowingText)%3B%0A%20%20%20%20%20%7D%2C%201000)%3B%0A%0A%20%20%20%20%20return%20()%20%3D%3E%20clearInterval(toggle)%3B%0A%20%20%7D)%0A%0A%20%20if%20(!isShowingText)%20%7B%0A%20%20%20%20return%20null%3B%0A%20%20%7D%0A%0A%20%20return%20%3CText%3E%7Bprops.text%7D%3C%2FText%3E%3B%0A%7D%0A%0Aconst%20BlinkApp%20%3D%20()%20%3D%3E%20%7B%0A%20%20return%20(%0A%20%20%20%20%3CView%20style%3D%7B%7BmarginTop%3A%2050%7D%7D%3E%0A%20%20%20%20%20%20%3CBlink%20text%3D'I%20love%20to%20blink'%20%2F%3E%0A%20%20%20%20%20%20%3CBlink%20text%3D'Yes%20blinking%20is%20so%20great'%20%2F%3E%0A%20%20%20%20%20%20%3CBlink%20text%3D'Why%20did%20they%20ever%20take%20this%20out%20of%20HTML'%20%2F%3E%0A%20%20%20%20%20%20%3CBlink%20text%3D'Look%20at%20me%20look%20at%20me%20look%20at%20me'%20%2F%3E%0A%20%20%20%20%3C%2FView%3E%0A%20%20)%3B%0A%7D%0A%0Aexport%20default%20BlinkApp%3B" data-snack-platform="web" data-snack-supported-platforms="ios,android,web" data-snack-theme="light" data-snack-preview="true" data-snack-loading="lazy"></div><p>In a real application, you probably won't be setting state with a timer. You might set state when you have new data from the server, or from user input. You can also use a state container like <a href="https://redux.js.org/" target="_blank" rel="noopener noreferrer">Redux</a> or <a href="https://mobx.js.org/" target="_blank" rel="noopener noreferrer">Mobx</a> to control your data flow. In that case you would use Redux or Mobx to modify your state rather than calling <code>setState</code> directly.</p><p>When setState is called, BlinkApp will re-render its Component. By calling setState within the Timer, the component will re-render every time the Timer ticks.</p><p>State works the same way as it does in React, so for more details on handling state, you can look at the <a href="https://reactjs.org/docs/react-component.html#setstate" target="_blank" rel="noopener noreferrer">React.Component API</a>. At this point, you may have noticed that most of our examples use the default text color. To customize the text color, you will have to <a href="/docs/next/style">learn about Style</a>.</p></div></article><div class="docMetadata margin-vert--xl"><div class="row"><div class="col"><a href="https://github.com/facebook/react-native-website/blob/master/website/../docs/state.md" target="_blank" rel="noreferrer noopener"><svg fill="currentColor" height="1.2em" width="1.2em" preserveAspectRatio="xMidYMid meet" viewBox="0 0 40 40" style="margin-right:0.3em;vertical-align:sub"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this page</a></div><div class="col text--right"><em><small class="docMetadata-updated">Last updated on <time datetime="2020-05-15T20:34:40.000Z" class="docLastUpdatedAt_1gIo">5/15/2020</time></small></em></div></div></div><div class="margin-vert--lg"><nav class="pagination-nav" aria-label="Blog list page navigation"><div class="pagination-nav__item"></div><div class="pagination-nav__item pagination-nav__item--next"></div></nav></div></div></div><div class="col col--3"><div class="tableOfContents_3iuQ"></div></div></div></div></main></div></div><footer class="footer footer--dark"><div class="container"><div class="row footer__links"><div class="col footer__col"><h4 class="footer__title">Docs</h4><ul class="footer__items"><li class="footer__item"><a class="footer__link-item" href="/docs/getting-started">Getting Started</a></li><li class="footer__item"><a class="footer__link-item" href="/docs/tutorial">Tutorial</a></li><li class="footer__item"><a class="footer__link-item" href="/docs/components-and-apis">Components and APIs</a></li><li class="footer__item"><a class="footer__link-item" href="/docs/more-resources">More Resources</a></li></ul></div><div class="col footer__col"><h4 class="footer__title">Community</h4><ul class="footer__items"><li class="footer__item"><a class="footer__link-item" href="/help">The React Native Community</a></li><li class="footer__item"><a class="footer__link-item" href="/showcase">Who's using React Native?</a></li><li class="footer__item"><a href="https://stackoverflow.com/questions/tagged/react-native" target="_blank" rel="noopener noreferrer" class="footer__link-item">Ask Questions on Stack Overflow</a></li><li class="footer__item"><a href="https://github.com/facebook/react-native/blob/master/CONTRIBUTING.md" target="_blank" rel="noopener noreferrer" class="footer__link-item">Contributor Guide</a></li><li class="footer__item"><a href="https://dev.to/t/reactnative" target="_blank" rel="noopener noreferrer" class="footer__link-item">DEV Community</a></li></ul></div><div class="col footer__col"><h4 class="footer__title">Find us</h4><ul class="footer__items"><li class="footer__item"><a class="footer__link-item" href="/blog">Blog</a></li><li class="footer__item"><a href="https://twitter.com/reactnative" target="_blank" rel="noopener noreferrer" class="footer__link-item">Twitter</a></li><li class="footer__item"><a href="https://github.com/facebook/react-native" target="_blank" rel="noopener noreferrer" class="footer__link-item">GitHub</a></li></ul></div><div class="col footer__col"><h4 class="footer__title">More</h4><ul class="footer__items"><li class="footer__item"><a href="https://reactjs.org/" target="_blank" rel="noopener noreferrer" class="footer__link-item">React</a></li><li class="footer__item"><a href="https://opensource.facebook.com/legal/privacy" target="_blank" rel="noopener noreferrer" class="footer__link-item">Privacy Policy</a></li><li class="footer__item"><a href="https://opensource.facebook.com/legal/terms" target="_blank" rel="noopener noreferrer" class="footer__link-item">Terms of Service</a></li></ul></div></div><div class="text--center"><div class="margin-bottom--sm"><a href="https://opensource.facebook.com" target="_blank" rel="noopener noreferrer" class="footerLogoLink_19Ac"><img class="footer__logo" alt="Facebook Open Source Logo" src="/img/oss_logo.png"></a></div><div>Copyright © 2021 Facebook, Inc.</div></div></div></footer></div>
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